Suppression of distinct ovo phenotypes in the drosophila female germline by maleless(-) and Sex-lethal(M)

Mutations in ovo result in several different phenotypes, which we show are due to the regulation of distinct developmental pathways. Two X (female) ge rm cells require ovo(+) activity for viability, but 1X (male) germ cells do not, in our study we observed suppression of the ovo germline-lethality ph enotype in loss-of-function maleless (mle) Females indicating that ovo(+) a nd mle(+) have opposing effects in female germ cells, or that they are hier archically related. Gain-of-function Sex-lethal (Sxl) alleles and male spec ific lethal-2 alleles did not suppress he ovo germline death phenotype. Man y of the surviving germ cells in females mutant for both ovo and mle showed ovarian tumors. in contrast to the germline viability phenotype, we did ob serve suppression of the tumor phenotype in females heterozygous for gain-o f-function alleles of Sxl. Further, females mutant for some hypomorphic ovo alleles were rendered fertile by Sxl gain-of-function alleles. Thus, ovo() is required For at least two distinct functions, one involving mle(+), an d one mediated by Sxl(+) gene products. The existence of ovo(+) functions i ndependent of mle(+) and Sxl(+) is likely. Dev. Genet. 23:335-346, 1998. (C ) 1998 Wiley-Liss, Inc.dagger